Russia has arrested four people on suspicion of plotting to assassinate senior defence officials and their families on Ukraine’s orders, the Kremlin’s Federal Security Service (FSB) said. 

The arrests come after Kyiv killed Igor Kirillov, the lieutenant general who was chief of Russia’s nuclear, biological and chemical protection troops, by detonating a bomb outside his apartment building in Moscow on Dec 17.

In a statement on Thursday, the FSB said that it had foiled “a string of assassination attempts planned by Ukrainian intelligence agents targeting senior officers of the Russian Defence Ministry involved in the special military operation, as well as their family members”.

The suspected organisers of the attacks were planning to use a remote-controlled car bomb to kill one of the officers, the FSB added.